Chinese astronomy

Astronomical ideas played an important part in the culture of China. An
Anyang bone inscription records a lunar
eclipse "on the fifteenth day of the twelfth moon of the twenty-ninth
year of King Wu-Ting (Nov. 23, 1311 BC)." In 1137
BC, the Shang Emperor Ti-hsin is recorded as ordering
a sacrifice because the predicted lunar eclipse fell on the wrong day. By
700 BC the Chinese observed the shadows of the Sun
from special towers, which remained in continuous use for determining calendars
for 1,500 years. By 350 BC the length of the solar
year was known to be 365¼ days, based on the helical
rising of Spica. Cosmological ideas were
interwoven with the Chinese world concept, which embodied the knowledge
of the celestial sphere with its daily rotation
around a pole. The horizon played a role, but the planets were not considered
important, although their motions were noticed.

Chinese
lunar calendar and importance of the pole

The Chinese perceived Heaven to be round. It had nine levels; each of which
was separated by a gate and guarded by a particular animal. The highest
level, the Palace of Purple Tenuity, was where the Emperor of Heaven lived
in the constellation we call Ursa Major. At the center of Heaven was the
North Pole and the polar star.

The celestial pole was a critical characteristic of Chinese cosmology. To
the Chinese, the center was the most important geographical point because
it was the closest to Heaven. They believed that the heart of civilization
lay at the center of the earth, and as the land spread out, the lands and
its inhabitants became more savage. Naturally, this emphasis on the center
point lead to the polar axis as a pivotal aspect of Chinese astronomy.

While the Greeks focused on the constellations on the horizon and created
a solar calendar, the Chinese observed the circumpolar stars, which lead
them to devise a lunar calendar instead. The polar axis which ran from the
polar star, south to Earth was the pivot of the heavens. The heavenly vault
slid up and down this axis while the earth itself oscillated along it to
create the seasons. The stars around the pole were also an integral part
of Chinese cosmology. The circumpolar stars were the key constellations
to the lunar mansions of the hsiu. At the equator, the Chinese divided the
sky arbitrarily into twenty-eight divisions, each corresponding to a equatorial
and a circumpolar constellation. Based on which mansion the moon occupied
at night, the Chinese created their lunar calendar.